Police officers direct traffic on eastbound Market Street to turn right at Sixth Street in San Francisco on Tuesday.

Photo: Paul Chinn, The Chronicle

Police officers direct traffic on eastbound Market Street to turn...

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Bicycle commuters have room to ride on eastbound Market Street after traffic was forced to turn right at Eighth Street in San Francisco on Tuesday. Taxis, buses, commercial vehicles and bicyclists are exempt in the six-week pilot program, which started today, and is designed to ease congestion on Market Street through the dense downtown core.

Photo: Paul Chinn, The Chronicle

Bicycle commuters have room to ride on eastbound Market Street...

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Police officer Dave Kranci stops a motorist from travelling eastbound on Market Street and forces them to turn right at Eighth Street in San Francisco Tuesday morning.

Photo: Paul Chinn, The Chronicle

Police officer Dave Kranci stops a motorist from travelling...

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A police officer directs cars driving on eastbound Market Street to turn right onto Eighth Street in San Francisco.

New signs (left) were posted on eastbound Market Street directing drivers to turn right at Eighth Street in San Francisco on Tuesday. Taxis, buses, commercial vehicles and bicyclists are exempt in the six-week pilot program, which started today, and is designed to ease congestion on Market Street through the dense downtown core.

Photo: Paul Chinn, The Chronicle

New signs (left) were posted on eastbound Market Street directing...

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Bicyclists roll past police officers assigned to divert cars travelling eastbound on Market Street to turn right at Sixth Street in San Francisco on Tuesday.

Photo: Paul Chinn, The Chronicle

Bicyclists roll past police officers assigned to divert cars...

Image 7 of 7

Police officer Dave Kranci stops a motorist from travelling eastbound on Market Street and forces him to turn right at Eighth Street in San Francisco on Tuesday. Taxis, buses, commercial vehicles and bicyclists are exempt in the six-week pilot program, which started today, and is designed to ease congestion on Market Street through the dense downtown core.

The city-run experiment to reduce traffic on San Francisco's Market Street kicked off Tuesday with few reported problems and a lot of promise for a city intent on promoting alternatives to driving.

The day began with traffic cops directing private cars off eastbound Market Street at Eighth and Sixth streets in a six-week trial to make the busy traffic corridor safer for pedestrians and bicyclists and less congested for the 12 Muni lines that use the thoroughfare.

While some drivers appeared confused, the officers patiently waved them toward their new - unintended - destinations.

Drivers who disobey the new traffic rule face a $167 fine, although authorities plan to issue warnings - not citations - for now.

The first bottleneck cropped up midday, starting just west of Ninth Street, when drivers had to sit through several cycles of traffic signals to travel one block. The holdup was at Eighth Street, where cars had to wait for pedestrians to cross in front of them before they could turn right.

Once past that choke point, however, what traffic remained ran smoothly. On many blocks, bikes outnumbered cars on Market Street, which is usually clogged with traffic.

"I've not seen anything like this on a weekday," said David Levine, a restaurant manager who commutes on bike down Market Street to his job on the Embarcadero. "There are still buses and trucks, but there's more room, less need to zigzag."

Alternatives suggested

During the trial, cars heading east on Market Street toward the Ferry Building must turn right onto Eighth and Sixth streets and find alternative routes to get downtown. Transportation planners suggest Mission and Folsom. Congestion did not surge on those streets through the early afternoon. But the big test will come during evening commutes. Folsom is a major feeder street to the Bay Bridge.

Officials hope to discourage drivers from using the well-known Market Street corridor that runs from Eureka Valley to the Financial District as a thoroughfare.

Cars are not being diverted off Market Street east of Sixth Street. In addition, the new rules do not apply to commercial trucks, taxis and buses. Westbound traffic is not affected.

City officials met after the morning commute to debrief and propose tweaks.

They decided they needed to post more traffic signs and portable electronic message boards further west to warn drivers of the forced turns. They also suggested having officers hold back pedestrians crossing Eighth Street before the light changes to red to give drivers more time to turn.

Cyclists also have to get used to the changes and pay extra attention to the right-turning cars, officials said.

Mayor Gavin Newsom and other political, civic and business leaders are eager to transform Market Street into a more vibrant boulevard, and, at one time, considered an all-out ban on cars. That proposal was dropped, but the question of how to remake the street has been a challenge for decades. One idea is to pursue a more pedestrian-friendly model to help spark the makeover, and the car restrictions put into place Tuesday are considered a first step.

Seedy target

The target is the mid-Market area - a seedy stretch between Van Ness Avenue and Powell Street that is pocked with sidewalk drug deals, public drunkenness and panhandling. Over the next year, the city plans to install new landscaping and street furniture. Newsom said the forced-turn pilot project will be abandoned if it doesn't show positive results.

Restricting cars on Market Street is the latest project by City Hall - as described by Newsom - "to democratize our streets." Short stretches of 17th Street in the Castro neighborhood and the road where San Jose Avenue and Guerrero Street converge in the Mission District have been closed temporarily and turned into mini-plazas, and more are planned.